Motor-control system.



H. L. BEACH.

MOTOR CONTROL SYSTEM. APPLICATIUN FILED FEB. 3.19m.

1,3 38. Patented Apr. 15,1919.

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o o og ard I eac I UNITED STATES PATENT OFFICE.

HOWARD L. BEACH, F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 01 rmmsynvaxm.

MOTOR-CONTROL SYSTEM.

Patented Apr. 15, 1919.

Application filed February 8, 1915. Serial No. 5,896.

To all whom it may concern Be it known that I, HOWARD L. BEACH, a cltlzen of the United States, and a resident of Edgewood Park, in the county of My invention relates to motor-control systems, and it has particular reference to such systems as are employed in connection with hoists, machine tools'and similar machines.

* My invention has for its object to pro- -tr1c motor may be operated 'at substantially I reversals are necessary, it is desirable to obtain operating conditions whereby the movmg parts may always be brought to a stop at the end of a definite and uniform extent of travel after the controller has been brought to the off position.

To accomplish the above result, I provide an arrangement by means of which a shunt circuit for dynamic braking is automatically established before the last step of the usual starting resistor has been inserted in circuit with the motor armature. A double-throw switch operates, in one position, to shunt an intermediate section of the resistor and to open the dynamic braking circuit. In its other position, the switch inserts the resistor section in circuit with the motor armature and closes the dynamic braking circuit.

The details of my invention are described in connection with the accompanying drawings in which Figure 1 is a diagrammatic view of circuits and apparatus embodying my invention. Fig. 2 1s a view, similar to Fig. 1, of a schematic arrangement of the system of Fig. 1. Fig. 3 is a diagrammatic view illustrating the sequence of the several switchesl Figs. 4 to 8, inclusive, are diagrammatic views of the circuits formed through the motor. 7

Referring particularly to Figs. 1 and 2,

line conductors 1 and 2, which may be connected to any suitable source of current, supply energy to an electric motor 3 havin a compensating field magnet wmdmg 4, a

vide a simple arrangement whereby an elecseries field winding 5 and a shunt field magnet winding 6. A starting resistor 7 of the usual sectional type is in series with the motor armature. connection of the motor to the line conductor 1. The starting resistor"? is controlled by a series of progressively actuated electromagnetic switches 9, 10 and 11 which operate, according to their positions, to remove sections of the starting resistor from, or insert them into, the motor circuit.

The 'dynamic braking circuit for the motor is controlled by an electromagnetic switch 12 which is mechanically connected to the switch 10 to form a double-throw switch. An electromagnetic switch 13 conin series with the shunt field magnet wind- The double-throw switch, comprising the switches 10 and 12, is-controlled by magnet coils 15 and 16 which'ioperate, according as the one or the other} exerts the stronger force, to close the switch 10 and open the switch 12, or to close the switch 12 and 0' en the switch 10. The coil.16 is designe to operate when the voltage applied to its terminals is approximately one-half that normally necessary for the operation of the 'coil 15. For example, if the coil 15 be adapted for operation at 230 volts, the coil 16 operates at 115 volts.

A resistor 17 is connected in shunt relation to the coil 15 and its resistance is'so ar- A main switch 8 controls the .70 'trols a shunt circuit for a resistor 14' that is ranged that the total resistance of the'parallelcircuit compris ng it and the coil 15, is substantially e ual to the resistance of the coil 16. Thus, w en the coils 15 and 16 are in series relation, the voltages applied to the terminals of the respective coi s will be equal. The coil 16 will, in such cases, predominate because the voltage a plied to the terminals 15 is only one-hal its normal value. When the 0011 16 is shunted, full volta ,is applied to the coil 15, and the switc es 10 and 12 are actuated in the opposite direction.

Normally, the switch12 is closed b a.

' circuit whichextends from the positive ine conductorl through conductors 18, 19 and 20, coils 15 and 16, switch 21 and conductors 22 and 23 to the ne ative line conductor 2. A shunt circuit for t e coil 15 extends from :the conductor 18 through the resistor 17.

t the line conductor To start the motor, a switch 24, which may be a push button located at any convenient point, is temporarily closed by the operator. Current then traverses a circuit extending from the line conductor 1 through the conductor 18, coil 25 of switch 8, conductor 26 switch '24, switch 27 which is closed, ant conductors 28 and 23 to line conductor 2. Current also flows from the conductor 18 through conductor 29, resistor 30, coil 31 of relay.switch 32, conductor'26 and then as abovetraced.

The" switch 8 is thereb actuated to close the motor circuit throng the entire starting resistor 7.,Current also traverses the shunt circuit for the motor armature controlled by the switch 12.. The relay switch 32 closes to complete a circuit which extends from theconductor'18 through the coil 25, switch 32, conductor 33,'switch 27 and conductors 28 and 23 to line conductor 2. This circuit connects the several controlling switches to the line conductor 1 after the starting button 24, has been released by the operator. 7

The closing of the switch 24 operates, also, to complete a circuit which extendsfrom the line conductor lthrough conductors 18 and 19, coil 34 of'switch 13, resistor 35, conductor 26 and thence to the line conductor 2, as traced above in connection with switch 8. The switch 13 is thus closed simultaneously withthe switch 8 to shunt the field resistor 14 and thereby insure a strong magnetic field in starting. The circuit formed through the'motor is illustrated in Fig. 4 of the drawing.-

. The closm of the switch 8 operates to permit the c osing of a relay switch 36 which controls the circuit-of the magnet coil 37 of the switch 9. The coil 37 is energized by a circuit which extends from the conductor 18, which is connected to the line conductor 1, through'a conductor 29, coil 37 relay switch 36 and conductors 22 and 23 to 1. The closing of the to shunt a section of the as is illustrated in Fig. 5 switch 9 also operates to ermit the. closin ofa relay switch 39 which establishes a s unt circuit for the coil 16. This shunt circuit extends from one terminal of the coil .16, through the rela switch 39, conductor 40, switch 41, switch 2 conductors 28 and 22 and switch 21 to the other terminal of the coil 16.

switch 9 operates startin resistor '7, of the rawing. The

The coil 16, which. operates as a holding L coil to maintain the closure of the switch 12,

is deenergized, and the voltage applied to the coil 15 is increased to'that of t e line conductors 1 and 2. The

coil 15 then operates to simultaneously close the switch 10 and to open the switch 12.

1 switch 10 operates to shunt a second section The opening of y The closing of the of the starting resistor 7 29, 18 and 19 to the switch 12 opens the shunt circuit for the motor armature, and the motor is further accelerated. The circuit formed through the motor is illustrated in Fig. 6 of the drawing.

The actuation of a rod 42, which connects the switches 10 and 12, permits the closing of a relay switch 43 which completes a circuit for the magnet coil 44 of the switch 11 46, auxiliary switch 47, conductors 48, 45, the upper terminal of coil 34. The switch 13 then opens a shunt circuit for the field resistor 14, and the motor is further accelerated because of its weakened magnetic field. The motor then operates at normal speed. The circuit formed through the motor is illustrated in Fig. 8 of the drawing.

During operation of themotor and the mechanism to which it is operatively connected, the speed may push button switch 41. When the switch 41 s closed, the motor runs at full speed, under normal conditions. The opening of the switch 41 opens the shunt circuit for the coil 16 and opens the circuit of coil 15. The switch 10 then opens by force of gravity and, when the rod 42 has completeda portion of its movement the auxiliary switch 21 is again closed. The coils 15 and 16 are thereby connected in series, and the coil 16, which is then'the'stronger, closes the switch 12 to establish the shunt circuit for the motor armature through the dynamic braking resistor 49.

The switch 21 is necessary, for, if it were omitted, the openlng of the shunt circuit for the coils 15 and 16 in series relation would operate to simply insert the resistance of coil-16 in circuit with coil 15. While the force exerted by' the latter coilwould be reduced, it would probably-be sufiicient to retain the switch '10 in its closed the coil 16 to connect for the magnet coil 34 be controlled by the position because the magnetic circuit of the coil 15 is closed and that of the coil 16 is I open. Under such circumstances, it would be impossible to operate the double-throw switch. The switch 21 renders it-possible to open the circuit-of coil 15 and thereby ermit the double-throw switch to equa ize magnetic conditions before the series circuit isagain completed.

The movement of the rod 42 opens the reinsert a section of the resistor 7 in circuit with the motor armature. The opening of switch 11 opens the auxiliary switch 47 which controls a shunt circuit for the coil 34 of switch 13. The latter switch then closes to establish a shunt circuit for the field resistor 14. The motor then operates at a relatively low speed because of the increased resistance of its armature circuit, the strengthened magnetic field and the shunt around the armature.

The speed of the motor, under the abovedescribed conditions, will be substantially constant for varying loads. When the appropriate switch or the controller, as the case may be, is adjusted to the ofi position, the travel of the mechanism before coming to rest is through a substantially uniform distance. The operator is thus enabled to stop the mechanism at'a desired point with a. considerable degree of accu-' racy.

To stop the motor, the switch 27 is opened to break the circuit of the coil 25 of the switch 8. The opening of the switch 8 opens the relay switch 36, and the coil 37 of switch 9v is deenergized thereby. The opening of the switch 27 also opens the circuits of coil 31 of the relay switch 32 and the coil 34 of switch 13, and the latter opens to again insert the resistor 14 in circuit with the shunt field winding. The motor is then brought quickly to rest by the dynamic braking action provided bythe circuit comprising the motor armature, resistor 49, switch 12 and field magnet winding 4.

To stop the motor when operating at full speed, it 1s only necessary to open the switch 27, whereupon the relay switch 32, which connects'the control circuits to the line conductor 1, opens the circuits of the coils of the severalswitches, and dynamic braking conditions are immediatel established. 4

An important feature 0 the system above described is that the control of the motor to produce the various operating conditions is accomplished. entirely by electromagnetic switches having coils that are connected in shunt relation to the motor. The employment of controlling mechanism capable of carrying heavy currents is thereby avoided.

I claim as my invention:

1. In a motor-control system, the combination with a switch, of electro-responsive controlling means therefor, said means comprising a pair of coils disposed in series-circuit' relation and adapted for operation at diiierent voltages, and means for shunting one of said coils to effectthe operation of said other coii at one of said voltages and for short-circuit ng the other or" said coils to efi'ect the operation of said one coil at said other voltage.

2. The combination with a double-throw switch, of means for actuating said switch in opposite directions, said means comprising two normally energized coils adapted for operation at different voltages, one only of said coils being normally ineffective and said other coil only being normally eifective to actuate said switch, and means for shunting said other coil to render said one coil effective to actuate said switch.

3. The combination with an electric system comprisin a pluralityof electric circuits, of a dou le-throw switch for controlling one of said circuits in one of its two positions and another of said circuits in the 30 other of said two positions, two actuating coils for said switch adapted to be energized to different degrees, means for connecting said coils in series to cause one of said coils to actuate said switch to one of said positions, and means for shunting said one coil to cause said other coil to actuate said switch to said other position.

4. In a motor-control system, the combination with a double-throw switch, and two coils for actuating said switch in opposite directions, of means for successively connecting said coils in series relation and energizing them to difi'erent degrees, shunting one of said coils, opening the circuit of the one coil, opening the circuit of the other coil andagain connecting them in series relation.

- electromagnets having actuating coils nor- I mally connected in series relation for actuating said switch in opposite directions, said electromagnets, when said coils are connected in series relation, operating to bias said switch from a central position to the low-speed position, and means for energiz ing said coils.

6. The combination with an electric system com rising a plurality of electric circuits, a tihuble-throw switch for, completing a circuit of the system in each position thereof, and two actuatin coils therefor, one of which is adapted to he excited to a less degree than the other when they are connected in series relation, of means for connectingsaid coils in series to actuate the switch to one of its operative positions and for shunts ing one of said coils to effect the movement of the switch to its other operative position.

7. In a motor-control system, the combination with an electric motor, and a plurality of controlling circuits therefor comprising resistors connected in series and in parallel relations with said motor, of a twoposition switch for controlling one of said circuits in each position thereof and means for actuating said switch comprising a pair ate said switch when ofelectromagents one of which is adapted to nation with a double-throw switch, of means coils disposed in series-cir comprising two actuating sald switch in opcuit relation for posite directions,.a resistor. for shunting one of said coils to efi'ect operation of the switch in one direction, and means for shunting the second coil to eifect operation of the switch in a reverse direction.

9. In a motor-control system, the combination with a motor and a source of power therefor, of means for connecting said motor to said source, a double-throw switch for controlling the circuit of said motor when it occupies one position and for controlling an additional. dynan'iic-braking circuit when it occupies another position, and means for causing said switch to assume said two positions, said means comprising two coils adapted for operation at difierent voltages, one of said coils being jineifective to actuboth of said coils are energized. v v

10. In a motor-control system, the combination with a double-throw switch, of two coils in series-circuitarelation for actuating said switch in opposite directions, one of said coils being adapted for operation at one half the voltage of said other coil, and a' resistor in parallel relation to said other coil, the resistance of the parallel circuit comprising said other coil and said resistor being equal to the resistance of said one coil.

11. In a motor-control system, the combination with a motor having an armature, a

resistor in series with said armature and a resistor in parallel with said armature, of a double-throw switch, a pair of coils for actuating said switch in one direction to close the circuit of said parallel resistor when both of said coils are energized and for actu-' ating said switch in the opposite direction to 0 en said circuit and to short-circuit a portlon of said series resistor when one of said coils is short-circuited, means for energizing both of said coils, and means controlled by the short-circuiting of a second portion of said series resistor for short-circuiting said one coil. 3 12. In a motor-control system, the combination with a motor and double-throw switch for controlling the same, of a pair of coils for actuating said double-throw switch, and a switch mechanically connected to said double-throw switch for controlling said coils.

13. In a motor-control system, the combination with a motor having a resistor, of a switch for closing the circuit of said motor, a switch for controlling said resistor, an actuating coil for each of said-switches, a switch for simultaneously closing the circuits of said coils, a switch for shunting said third-named switch, and an actuating coil for said fourth-named switch, the circuit of said last-named coil being closed by said I third-named switch simultaneously with the closing of said two first-named switches.

In testimony whereof, I. have hereunto subscribed my name this th day of Jan. 1915.

Witnesses: B. B. Hmns,

HOWARD L. BEACH. 

